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Feasibility of 120V daily charging with 240V backup?

ratsbew

Active Member
Mar 3, 2012
1,293
1,043
O'Fallon, IL
I'm trying to plan out my Model 3 charging strategy given that my garage isn't wired with 240V. My commute is only about 20 miles total per day so 120V should work 99% of the time. Weekend trips might take my battery down to 10% upon reaching home, but I can just charge at 120V every night during the week to gradually reach a higher SOC every morning.

My electric dryer plug is inside the house right inside the garage door so the UMC should be able to reach. My thoughts are that I can unplug the dryer on the rare occasion where I need to top off quickly at home (coming home from work and heading out soon on a road trip). This should only be a couple of times per year.

Is there anything wrong with planning on trickle charging at 120V 99% of the time as long as I have the option of unplugging my dryer for quick charging? Is 120V less efficient wall-to-wheel?
 
Location matters, if your location gets cold I really think you will find 120volt does not work so well in winter. I say this as someone who got by for weeks in summer on a model S with a 120volt outlet, but winter not a chance, and as said 240volt is more efficient due to reducing the duration of chargers and software being active.
 

TexasEV

Well-Known Member
Jun 5, 2013
7,652
8,918
Austin, TX
You’ll enjoy the car a whole lot more if you’re not having to think how many miles charge you have. It’s a whole different experience waking up to a 80% or 90% charge every morning, with ability to make that 100% if you want to. I recommend installing a NEMA 14-50 outlet (as Tesla recommends) and just consider that part of the price of the car.

Just saw your near simultaneous post as mine— a 240V outlet is not a “substantial investment” for most houses.
 
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Zoomit

Active Member
Sep 1, 2015
2,293
4,489
SoCal
It's easy for others to spend your money. I have a different opinion, based on my experience. I'm currently charging 2 EVs, driving a combined 25k mi/yr. One is recharged at 1.4kW ([email protected]) and the other at 2.8kW ([email protected]). There's no doubt that faster charging will be easier, but your strategy is very legitimate.

Yes, 240v charging is more efficient but the cost-benefit trade is pretty simple. Say you drive 10,000 mi/yr, which may be high if you have only a 20mi total commute. Over 4 years that's 40,000 mi which might use 10,000kWh (@250Wh/mi wall-to-wheel). Assuming you charge at $0.15/kWh, that's $1500 in electricity. If the difference between 120v and 240v charging increases losses by 10%, it'll cost you an additional $150 to charge via 120v over that time.

I made a similar calculation and certainly couldn't justify spending $1500, in my case, to add a NEMA 14-50 given my break-even duration. I also considered that the addition of the outlet would not appreciably increase the value of the house; again your situation may be different.

If you drive 25 miles per day, that's only about 6 hours of recharging time on [email protected] If you actually recharge for 8-10 hrs per day, you can make up busier days slowly, or just use your dryer outlet.

I recommend trying it for a few months before committing.
 

FlatSix911

Porsche 918 Hybrid
Jun 15, 2015
7,468
7,674
Silicon Valley
I'm trying to plan out my Model 3 charging strategy given that my garage isn't wired with 240V. My commute is only about 20 miles total per day so 120V should work 99% of the time. Weekend trips might take my battery down to 10% upon reaching home, but I can just charge at 120V every night during the week to gradually reach a higher SOC every morning.

My electric dryer plug is inside the house right inside the garage door so the UMC should be able to reach. My thoughts are that I can unplug the dryer on the rare occasion where I need to top off quickly at home (coming home from work and heading out soon on a road trip). This should only be a couple of times per year. Is there anything wrong with planning on trickle charging at 120V 99% of the time as long as I have the option of unplugging my dryer for quick charging? Is 120V less efficient wall-to-wheel?

The 120V solution should be fine for 8-10 hour charging.
If you want to charge faster at 240V there is no need to install a new outlet, just use the existing 30A dryer outlet. :cool:
Check out this product for a cost effective solution ... Dryer Buddy™

upload_2018-3-13_18-34-9.png
 
I am planning on doing the same thing - my daily commute is 20 miles round trip, and I’ll only be in my current home for another 3 to 4 months. However I will be installing a 50 amp outlet in the garage on my new house, as my commute will be longer and I want the flexibility.

I think your plan is solid - and you have the dryer outlet for those times you need a faster charge.
 
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FWIW my 3 will be my third EV (I plan on blasting Schoolhouse Rocks' "Three Is A Magic Number" as I drive it off the lot), and I only ever used the regular old 120v charger for both my 2011 Leaf and my 2014 Volt. I never drove either of them far enough that I felt like I needed a level 2 charger.

I probably still don't need a level 2 charger at home, but I wanted to get ready for my 3 and popped for a HPWC. It was an impulse buy that I don't think I'll regret. In your case though, you're probably safe with the regular outlet for most of your charging.
 
There is absolutely nothing wrong with charging regularly with a normal 120V outlet. I have been doing it with my Volt for the last 5 years. I get about 3-4 miles range per hour of charge. I go to bed empty and wake up full. Now, is a 240V or HPWC better? Sure, but it's kind of like "you never miss it if you've never had it". The only time you would really regret not getting 30-40 miles range per hour is if you were regularly traveling lots of miles on a daily basis.

120V is totally possible and practical when you look at the price of installing a 240V, J-1772, or HPWC. Now, having said all that, I just purchased a HPWC for my upcoming Model 3. My reasons stem more from convenience though. I don't want to continuously have to use the portable charge unit that comes with the car. I want to keep that neatly packed in its little case to be used on the road. I have gone through two charge cables on my Volt over 5 years from doing just that.

Dan
 
LOCATION MATTERS due to temperature.

What works just fine with 50degree nights doesn't mean it will work with 15degree nights. Consumption rises dramatically in cold climates too.

Not saying anyone is wrong just think this is getting to little attention.
Although I live in Georgia, we do have occasional nights that get well below freezing (10-20F). I have never had a problem charging my Volt while parked outside and running the cable under the garage door to the unheated garage where the outlet is. Just my experience.

Dan
 

PJFW8

Red Menace may hurt me
May 29, 2015
390
308
Hendersonville, NC
Although I live in Georgia, we do have occasional nights that get well below freezing (10-20F). I have never had a problem charging my Volt while parked outside and running the cable under the garage door to the unheated garage where the outlet is. Just my experience.

Dan
Dan, respectfully, I relocated to NC from Wisconsin. You can't appreciate the misery of 5 below zero temperatures (or even 20 bellow) day after day. If the car is outside or in an unheated garage, 240 is necessary. 5 to 10 above zero may stretch for weeks. I had a 240 charger (GE) for my CMax and Fusion Energi. Preconditioning was a life saver. Even today in NC it is great. 120 is fine for many in California and the South. It just is sub-optimal in the North.
 
Dan, respectfully, I relocated to NC from Wisconsin. You can't appreciate the misery of 5 below zero temperatures (or even 20 bellow) day after day. If the car is outside or in an unheated garage, 240 is necessary. 5 to 10 above zero may stretch for weeks. I had a 240 charger (GE) for my CMax and Fusion Energi. Preconditioning was a life saver. Even today in NC it is great. 120 is fine for many in California and the South. It just is sub-optimal in the North.
Fair enough. I was just sharing my experience. Certainly your mileage may vary.

Dan
 
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On a 30amp 240volt circuit my Model S can actually use a few miles preheating.......I know the M3 doesn't heat the battery the same way but this still will have an impact. Energy consumption is higher in cold weather, can double on short drives.

My employer brings up folks from GA all the time and let's just say they don't consider the winter weather comparable. We can have weeks that doesn't reach 10f.

Early winter I tried scheduled charging and the time to warm the battery screwed up finish time by a lot. Now I let it charge at plug in so the drive home has warmed it. Relying on 120volt you will obviously be aiming for Max time and plugging in on arrival and starting to charge but then you still have the increased consumption which I have seem double if I don't preheat off the wall.
 

scaesare

Well-Known Member
Mar 14, 2013
8,642
15,404
NoVA
I agree with the sentiments above that you can make this work. Especially if you suspect you may not be there long-term.
If you are garaged, any cold won't affect you that much.

I get 3.5-4 MPH rate on a 120V/15A circuit, and 5 MPH on a 20A circuit. I suspect the Model 3 getting 6 MPH is likely. If you plug in for 10-12 hours a night, gaining 60-70 miles of range is reasonable.

Another option: if your garage has a dedicated 15 or 20A circuit (many do), that you can convert to a NEMA 6-15 or 6-20 receptacle, you can charge at 240, and be looking at 10-12+ MPH of charging. You'd just need to change some breakers (assuming your panel can accommodate), and re-mark some already-existing wires. Then build/purchase a relatively inexpensive adapter. Probably less than $100 all told.
 
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